bertram31.com

I am running fresh water cooled 7.4 gas ----where should I be taking temp readings with a digital thermo?

And what is a good temp?

My gauges read 160 at cruising speed, engines fully warmed up. I’m using 160 degree thermostats. If you are concerned about anything, check the temperature of the manifolds, intake and exhaust, and cylinder heads for hot spots. The risers should be considerably cooler than the exhaust manifolds since they are cooled by a constant flow of raw water.

I shoot temps on motors as a comparison tool between motors and for what’s normal for your boat. The risers should never exceed what you can put your hand on for a few secounds, same with hoses and exhaust manifolds( aside from exhaust ports which get super hot. I feel for hot spots on hoses after the dump to be sure cooling water if flowing.
With IR gun temps should be within a few degrees between motors on similar items. Anything very different should be a red flag something may be off. Exact temps r tough as configurations change from one setup to the next.
What should be standard to spec is the engine coolant temp…your manual will tell you where it should run. But that internal coolant temp sensors, not some that can be verify with an IR gun.

Those engines can handle past 200 degrees about 210 to 215 before you start having failures. I wouldn't want my exhaust hose at those temps though. I think the max temp on regular shields marine are 250 degrees. I wouldn't run a marine engine over 185 for to long. A safe and comfortable temp is 165-175, or 5-10 degrees above your thermostat rating